1. Field of the Invention
This invention concerns a plastic crosscurrent heat exchanger body that is composed of a stack of extruded web plates and serves to exchange heat between flowing media. In contrast to a complete heat exchanger, including the supply and discharge lines for the flowing media in addition to the necessary collecting tanks, the term "heat exchanger body" herein is meant to imply only the arrangement of flow channels between which heat is transferred.
2. Discussion of the Related Art
Although plastics are generally poorer heat conductors than metals, plastic heat exchangers have attained considerable importance for applications involving a simple and inexpensive method of production and low material costs, which were not achievable with metal heat exchangers. The lower weight can also be crucial for the selection of plastic as the material for heat exchangers.
In any case, the economy of large heat exchanger systems, such as those used in dry-cooling towers or waste gas desulfurization systems, is critically affected by the expense of producing the heat exchanger body.
Extruded plastic web plates consisting of two planar, parallel cover layers and webs coextruded integrally with the cover layers located between them, which enclose parallel hollow flow chambers, are outstanding structural elements for heat exchanger bodies because of their low costs of production. According to DE-A No. 27 51 115, plastic web plates are cemented into a stack by means of an adhesive applied to the cover layers. According to EP-B No. 167 938, the stacked web plates in such an arrangement are connected to one another only in the facial area to simplify the production process, for example, by means of an intermediate hot wire that is heated above the melting point of the plastic by applying an electrical voltage, and leads to the welding of the adjacent plastic surfaces.
Crosscurrent heat exchanger bodies that are composed of extruded plastic web plates and contain a hollow flow chamber across them between each two parallel flow web plates, are also known from FR-A No. 2 469 684 and DE-A No. 31 37 296. In both cases, the web plates have a uniform profile up to their faces. None of these publications describe a joining technique that permits rapid and simple construction of a heat exchanger body from a number of web plates. A drawback of the known heat exchanger bodies is the unfavorable flow impact profile of the open faces.
In spite of the above approaches, there has remained a need for heat exchangers which are simpler, less expensive to produce, than metal heat exchangers.